Method of and apparatus for producing fibrous or filamentary material



July 21, 1936. c NORTON 2,048,651

METHOD OF AND APPARATUS FOR PRODUCING FIBROUS OR FILAMENTARY MATERIALFiled June 25, 1933 I72 venior."

M imam, 73

Patented July 21-, 1936 PATENT OFFICE DIETHOD OF AND APPARATUS FOR PRO-DUCING FIBROUS OR FILAMENTARY MATERIAL Charles L. Norton, Boston, Mass.,assignor to Massachusetts Institute of Technology, Cambridge, Masa, acorporation of Massachusetts Application June 23, 1933, Serial No.677,277

11 Claims.

This invention relates to the formation of filaments or fibers fromviscous material capable of relatively rapid solidification from aliquid condition, by expelling them from a container in which thematerial is held in liquid form either as the result of fusion or insolution in a volatile liquid. This is preferably done by an air blastin conjunction with an electrostatic attraction toward an adjacenttarget, as well as by the repulsion between the charged surface portionsof the liquid and other adjacent parts of the mass. It is well knownthat small particles when electrified by charges of like sign repel oneanother, whereas particles or masses of opposite sign are attracted.

The process may be applied to materials such as gums, pitches orsynthetic rosins, either molten or held in solution, and also to otherviscous materials such as glass in a fused condition. The container inwhich the liquid is held may be of metal or, if high temperatures arerequired, of porcelain or refractory clay, and the liquid therein iselectrically connected with one terminal or pole of a static machine orother source of high electric potential. The other terminal of thepotential source is electrically connected with a target or screen,which may be in the shape of a fiat plate or of a cylinder, and which,while spaced from the container, is sufficiently near the latter topermit of a considerable electrostatic attraction between the target andthe fibers as they emerge from the container. In carrying out theinvention I have used a multiple plate static machine capable of givingvoltages of the order of one hundred thousand volts or more. I have usedcontainers of metal, porcelain or refractory clay and have used targetsof galvanized iron maintained at a distance of from one to six feet fromthe container. With some low melting point materials, such as rosins,the targets can be placed at a distance of twenty feet or more. Thefilaments or fibers are formed by the blast of air and the electrostaticrepulsion from the surface of the liquid and fiy through the air towardthe target. They are all electrified in the same sign and are repelledboth by the mass of liquid in the container and by each other. Saidfibers, as they leave the liquid mass, solidify progressively and aredrawn out in continuous lengths, sometimes of a great many feet, as theyproceed from the surface of the liquid mass. Those which are expelledfrom solutionin alcohol, for instance, offer a very great surfacebecause of their fineness, so that evaporation is very rapid, and thefibers become solid almost immediately after their 1 expulsion from thesurface of the liquid.

In this manner, under the influence of the elec trostatic expulsion, incombination with the air blast, or with the attracting target, or both,fibers of extreme fineness can be made, which fibers are mutually sorepelled that they are rarely straight 5 and may therefore be used toproduce a fibrous mass well suited for packing, insulation, or similarpurposes. They may be made of a still more irregular or kinked contourby subjecting them, after their expulsion from the liquid mass andbefore their complete solidification, to an intermittent force actingtransversely to their direction of travel. This may be accomplished byarranging at opposite sides of the path of travel of the fibers twoelectrodes in the form of auxiliary targets upon which are superimposedan al ternating electromotive force, for instance, 60 cycles at 2200volts, so that the fibers, while emerging from the liquid and beforetheir complete solidification, receive sidewise impulses alternating inopposite directions, as they proceed toward the main target, causingthem to become still more crooked and irregular. The same type ofirregularity may be given to the fibers by subjecting them to theinfluence of a pulsating air 5 blast acting transversely to theirdirection of travel.

The electrostatic repulsion of the fibers from the liquid mass and fromeach other may be utilized either in conjunction with the electrostaticattraction of said fibers for an oppositely charged target, or inconjunction with the ordinary process of blowing glass or slag wool by ablast of steam or air under pressure, or both. I have succeeded inproducing fibers of great fineness and length and of kinky or irregularcontour by blowing viscous liquids over the edge of a container and atthe same time making the latter one terminal of a static machine whoseother terminal is electrically connected with a 40 large metallic targetor even with the floor and side walls of the room.

The point at which the liquid escapes from the container can becontrolled and the efficiency of the apparatus increased by providingthe container with a spout or lip and tilting it in the ordinary mannerso that, as material is supplied to it, said material tends to flow outover the lip. At this point electrification seems to be more intense,and the material, as it escapes from said lip, instead of falling orblowing out in the form of drops or coarse fibers, is scattered 1 aboutand shredded into fine threads which fly toward the target and oftenadhere for a time to it. 56

Preferably the melting of the material, where fusion is employed, isdone by means of electric -heaters, since the presence of hot gases fromheaters of the combustion type tends to cause excessive leakage of theelectrostatic charge from the liquid, although excellent glass wool hasbeen made by this method employing a gas and air furnace.

The invention will best be understood by the following description ofcertain forms of apparatus, illustrated in the accompanying drawing, bywhich it may be practiced. It will be appreciated, however, that theparticular apparatus and operations shown and described have been chosenfor purposes of exemplification merely, and that the invention, asdefined by the claims hereunto appended, may be otherwise embodied andpracticed without departure from the spirit and scope thereof.

In said drawing:

Figs. 1 and 2 are diagrammatic views illustrating two forms of apparatussuitable for practicing the invention.

Referring to Fig. 1, HI denotes a container for the material which maybe supplied thereto by a suitable feed chute or spout ll. Saidcontainer, which may be heated by any suitable means, such as anelectric heating unit or units II of any usual or well known type, isprovided with a discharge lip or spout II from which the liquid is blownby means of compressed air delivered from a suitable source to a nozzleit supported to deliver a blast in a direction away from the containerl0 toward a galvanized iron or other target Ii. In other words, theblast is delivered in the general direction of the target I! or of thefield. At It is shown a static machine having one pole or terminalelectrically connected with the target II and the other electricallyconnected with the liquid in the container ll, the connections beingmade in any usual or suitable manner. As shown, the positive terminal isconnected with the target and the negative pole with the container,although the polarity direction is relatively unimportant. Disposed atopposite sides of the path from the lip II to the target I 5 areelectrodes in the form of auxiliary targets I! connected respectivelywith the terminals of an alternating current generator i8.

In operation, due to the combined action of the air blast from thenozzle ll and the electrostatic repulsion above described, the liquidemerges from the lip II in the form of fibers which are immediatelyattracted to the target II. The air blast, used in conjunction with theelectrostatic repulsion. serves not only to draw out and remove thefibers as fast as they are formed by giving them a mechanical impulse inaddition to the electrostatic pull, but also to carry away the ionizedair which results from the brush discharge of the container and tends tomaintain a zone of conducting medium around the latter. Consequently theelectrostatic leakage from the container is diminished and theproduction of fibers greatly increased. Due to their mutualelectrostatic repulsion, said fibers tend to assume an irregular orkinky form which is intensified by the intermittent transverse force towhich they are subjected by the alternating electromotive force suppliedto the electrodes l'i. Upon striking the target II, the static chargescarried by said fibers are usually discharged, permitting said fibers tofall into a suitable receiving container I. If, as

aosacu may occur in some instances, the fibers tend to adhere to thetarget, they may be removed therefrom and delivered into said containerin any convenient manner.

The apparatus illustrated in Fig. 2 is substantially similar inprinciple to that shown in Fig. l with the following differences inconstruction. In lieu of the electric heating means ii, there isemployed a suitable gas and air mixing burner 20 for heating thecontainer ll, said burner discharging its flame into a suitable fire pot2i below said container. The target 22 is in the form of a rotatingcylinder provided with a doctor 23 for continuously removing therefromany fibers which may tend to adhere thereto. In lieu of 15 the auxiliarytargets I1 and alternating current generator ll, there is provided, forthe purpon of subjecting the fibers to a transverse intermittent force,a nozzle 24 directed crosswise of the path of travel of the fibers andsupplied with go compressed air from anysuitable source under thecontrol of a rotary or other pulsating valve 25. The operation of thisapparatus is substantially the same as that of the form first describedand requires no further explanation.

Referring to both forms, it will be observed that there is employed anelectrical field suitable regulating as to extent and intensity inconjunction with a mechanical impulse predetermined or controlled as todirection, location and :0 force, whereby substantially solidifiedfibers are formed within the field.

I claim:

1.. The method of forming fibers from viscous liquid capable of rapidsolidification which com- 8 prises expelling said liquid from a suitablecontainer while subjecting the fibers so formed, after their expulsionand before their complete solidification, to an alternatingelectromotive force acting transversely to their direction of travel.

2. The method of forming fibers from viscous liquid capable of rapidsolidification which comprises expelling said liquid from a suitablecontainer under joint electrostatic and mechanical impulse whilesubjecting the fibers so formed, after their expulsion and before theircomplete solidification, to an intermittent force acting transversely totheir direction of travel. 1

3. An apparatus for forming fibers from viscous liquid capable of rapidsolidification comprising, in combination, a container for the liquid,means for expelling said liquid from said container in the form offibers, and means for subjecting said fibers as they leave saidcontainer to an intermittent force acting transversely to the directionof their expulsion.

4. An apparatus for forming fibers from viscous liquid capable of rapidsolidification comprising, in combination, a container for the liquid, atarget spaced from said container, a source of static electricity havingone pole electrically connected with said liquid and the opposite poleelectrically connected with said target, a pair of electrodes locatedrespectively at opposite sides of the path from said container to saidtarget, and means for superimposing upon said electrodes an alternatingelectromotive force.

5. The method of forming fibers which comprises expelling a viscousliquid capable of rapid solidification from a body of such liquid while70 controlling the shape of the fibers so formed by subjecting them,after their expulsion and before their complete solidification, to anintermittent force acting transversely to their direction of travel.

6. The method of forming fibers from a viscous liquid capable of rapidsolidification from a body of such liquid which consists in creating anelectrical field between two poles and electrically propelling from onepole of the field toward the other, portions from the liquid body whilesubjecting such portions to mechanical impulse, regulating the extentand intensity oi said field and controlling the location, direction, andforce of said mechanical impulse in such manner as to form substantiallysolidified fibers in the field.

7. The method 01' forming fibers from a molten viscous liquid capable ofrapid solidification from a body of such liquid which consists increating an electrical field between two poles and electricallypropelling from one pole oi. the field toward the other, portions fromthe liquid body while subjecting such portions to mechanical impulse,regulating the extent and intensity of said field and controlling thelocation, direction, and force of said mechanical impulse in such manneras to form substantially solidified fibers in the field.

8. The method ofiorming fibers from a viscous liquid capable of rapidsolidification from a body of such liquid which consists in creating anelectrical field between two poles and electrically propelling from onepole of the field toward the other, portions from the liquid body whilesubjecting such portions to mechanical impulse in the form of a blast,regulating the extent and intensity of said field and controlling thelocation, direction, and force or said mechanical impulse in such manneras to form substantially solidified fibers in the field.

9. The method oi. for ng fibers from a molten viscous liquid capable ofrapid solidification from a body of such liquid which consists increating an electrical field between two poles and electricallypropelling from one pole of the field toward the other, portions fromthe liquid body while 5 subjecting such portions to mechanical impulsein the form of a blast, regulating the extent and intensity of saidfield and controlling the location, direction, and force of saidmechanical impulse in such manner as to form substantially solidifiedfibers in the field.

10. The method of forming fibers from a viscous liquid capable of rapidsolidification from a body 01 such liquid which consists in creating anelectrical field between two poles and electrically propelling from onepole of the field toward the other, portions from the liquid body andsubsequently subjecting such portions to mechanical impulse, regulatingthe extent and intensity of said field and controlling the location,direction, and force of said mechanical impulse in such manner as toform substantially solidified fibers in the field.

11. The method of forming fibers from a viscous liquid capable oi rapidsolidification from a body of'such liquid which consists in creating anelectrical field between two poles and electri-' cally propelling fromone pole of the field toward the other, portions from the liquid bodywhile subjecting such portions to mechanical impulse acting in thegeneral direction of the field, regulating the extent and intensity ofsaid field and controlling the location, direction, and force of saidmechanical impulse in CHARLES L. NORTON.

such manner as to i'orm substantially solidified fibers in the field.

